New technologies, as network functions virtualization (NFV) and software defined networks (SDN) have positive elements which reduce the deployment cost of the network elements, for example routers and switches.
NFV application to cellular networks was studied recently in the Small Cell Forum and NGMN Alliance.
SDN was applied to WiFi networks in different demos, based on the features and management interfaces of the IEEE 802.11a and IEEE 802.11k amendments. Based on these, an SDN Controller can allocate the power and select an operational channel.
3GPP LTE standards were designed for the distributed operation of the base stations and the CoMP (Collaborative Multi Point) standardized features were defined for distributed operation. The LTE architecture in Release 13, pictured in 3GPP TS 36.300 V13.0.0 (2015-06). FIG. 4-1 in this document does not include a Central Coordinator.
However some support for centralized coordination of inter-cell interference was introduced in LTE Release 12, but even in LTE Release 13 this support is limited only to a hypothesis on the assignment of time-frequency resources which should be protected by another base station, with no guarantee that the assignment will be indeed applied.
The limited support in 3GPP TS 36.423 Release 13 for central coordination has resulted in a high volume of measurement information, frequently above the up-link capacity of the VDSL base station backhaul.
In research papers appears the notion of network graph, presenting the wireless connection between different nodes as a visual characterization of the wireless network interactions.
As both the term “controller” and “coordinator” are used in the wireless industry, it is needed to clarify the difference between them: the “control” is defined as an activity to determine the behaviour of a network element. The “coordination” is defined as an activity to enable the efficient operation of the control functions, being situated at a level higher than the “control” of a network element.